| abstract |
The invention concerns compounds of formula (1) wherein in particular G represents the -N(CH3)2-, -N(C2H5)2-group or N-pyrrolidine; n is an integer equal to 1 or 2; R1, R2 and R3, independently of one another, represent a hydrogen atom or a methyl group, the successive unsaturated units capable of being moreover identical or different, provided that at least one of the substituents R1, R2 and R3 is different from H; and Y1 and Y2 represent each a -COOCH3 group or a -COOC2H5 group. |